title: ERECTA family genes regulate auxin transport in the shoot apical meristem and forming leaf primordia.
abstract: Leaves are produced postembryonically at the flanks of the shoot apical meristem. Their initiation is induced by a positive feedback loop between auxin and its transporter PIN-FORMED1 (PIN1). The expression and polarity of PIN1 in the shoot apical meristem is thought to be regulated primarily by auxin concentration and flow. The formation of an auxin maximum in the L1 layer of the meristem is the first sign of leaf initiation and is promptly followed by auxin flow into the inner tissues, formation of the midvein, and appearance of the primordium bulge. The ERECTA family genes (ERfs) encode leucine-rich repeat receptor-like kinases, and in Arabidopsis (Arabidopsis thaliana), this gene family consists of ERECTA (ER), ERECTA-LIKE1 (ERL1), and ERL2. Here, we show that ERfs regulate auxin transport during leaf initiation. The shoot apical meristem of the er erl1 erl2 triple mutant produces leaf primordia at a significantly reduced rate and with altered phyllotaxy. This phenotype is likely due to deficiencies in auxin transport in the shoot apex, as judged by altered expression of PIN1, the auxin reporter DR5rev::GFP, and the auxin-inducible genes MONOPTEROS, INDOLE-3-ACETIC ACID INDUCIBLE1 (IAA1), and IAA19. In er erl1 erl2, auxin presumably accumulates in the L1 layer of the meristem, unable to flow into the vasculature of a hypocotyl. Our data demonstrate that ERfs are essential for PIN1 expression in the forming midvein of future leaf primordia and in the vasculature of emerging leaves.
authors.affiliation: Department of Biochemistry, Cellular, and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors.forename: Ming-Kun
authors.initials: MK
authors.lastname: Chen
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Wilson
authors.forename: Klaus
authors.initials: K
authors.lastname: Palme
authors.forename: Franck Anicet
authors.initials: FA
authors.lastname: Ditengou
authors.forename: Elena D
authors.initials: ED
authors.lastname: Shpak
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D018519:Meristem / Q000235:genetics / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism; D005810:Multigene Family; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D018524:Phototropism / Q000235:genetics; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D030821:Plants, Genetically Modified; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C491592:IAA1 protein, Arabidopsis; C483308:IAA19 protein, Arabidopsis; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; D009687:Nuclear Proteins; C116363:PIN1 protein, Arabidopsis; D011956:Receptors, Cell Surface; C457763:ER protein, Arabidopsis; C502168:ERL1 protein, Arabidopsis; C502169:ERL2 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases; D020930:MAP Kinase Kinase Kinases; C481302:YODA protein, Arabidopsis; D020929:Mitogen-Activated Protein Kinase Kinases